Structural foundation

ABSTRACT

An object of the invention is to provide a structural foundation wherein a spiral pile for supporting the foundation can be fixed in such a stable manner as not to displace in the horizontal direction or not to subside in the vertical direction. The structural foundation can be easily installed on site with reduced costs for transportation and installment so as to support a structure or part of a structure. The structural foundation ( 3 ) has a foundation portion ( 2 ) to be fixed to the ground using a spiral pile ( 1 ), and is characterized in that the foundation portion ( 2 ) has a cylindrical steel tube ( 23 ) for guiding the spiral pile ( 1 ) and a portion ( 21 ) for receiving pressure in the horizontal direction, which is placed so as to surround the cylindrical steel tube ( 23 ), and the foundation portion ( 2 ) and the spiral pile ( 1 ) are provided with a fixing means ( 12, 22 ) for connecting the foundation portion ( 2 ) and the spiral pile ( 1 ) in a state where the spiral pile ( 1 ) is inserted into the cylindrical steel tube ( 21 ) and the spiral pile ( 1 ) is embedded in the ground.

FIELD OF THE INVENTION

The present invention relates to a structural foundation, and in particular, to a structural foundation having a foundation portion to be fixed to the ground using a spiral pile.

BACKGROUND ART

When a post is erected on the ground according to the prior art, a method for fixing the foundation installed in the ground with a pile, erecting a post on the foundation and fixing the post with mortar has been adopted. In particular, the present applicant has put into practice many methods where a spiral pile that is formed by twisting a flat steel plate is adopted as a pile for fixing the foundation.

For example, Patent Document 1 shows a spiral pile that is to be directly driven into the ground in order to provide the foundation for a post. Patent Documents 2 to 4 show a method for creating a hole in a concrete block foundation or a poured concrete foundation installed in the ground, driving a spiral pile into the ground through the hole and fixing the concrete foundation. Such a spiral pile can be easily installed by pouring concrete on site and has the advantage that it is highly resistant to being pulled out due to the fact that the friction with the ground is great.

While the above described spiral pile has a great resistance in response to the force in the direction in which the spiral pile is pulled out, the mechanical strength is weak relative to the stress that is placed on the spiral pile in the horizontal direction or relative to the compressive force in the vertical direction, and therefore the form of the spiral pile changes in the horizontal direction or in the vertical direction, which is a problem because the foundation becomes unstable. In addition, it is troublesome to prepare a concrete foundation where a hole through which a spiral pile can be passed is created. Furthermore, due to its size and weight, transportation and installment of this type of foundation is very costly.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japan Patent No. 4017922

Patent Document 2: Japan Patent No. 3836745

Patent Document 3: Japan Patent No. 4558905

Patent Document 4: Japan Patent No. 4585757

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

An object of the present invention is to solve the above-described problems and to provide a structural foundation that can support a structure in a stable manner where stress placed on the spiral pile that forms the foundation in the horizontal direction or in the vertical direction can be reduced. Another object is to provide a structural foundation that can be easily installed on site with reduced costs for transportation and installment.

Means for Solving Problem

In order to achieve the above-described objects, the invention according to claim 1 provides a structural foundation for supporting a structure or part of a structure, wherein the structural foundation has a foundation portion to be fixed to the ground using a spiral pile, and is characterized in that the foundation portion has a cylindrical steel tube for guiding the spiral pile and a portion for receiving pressure in the horizontal direction, which is placed so as to surround the cylindrical steel tube, and the foundation portion and the spiral pile are provided with a fixing means for connecting the foundation portion and the spiral pile in a state where the spiral pile is inserted into the cylindrical steel tube and the spiral pile is embedded in the ground.

The invention according to claim 2 provides the structural foundation according to claim 1, which is characterized in that the spiral pile has a spiral portion formed by twisting a flat steel plate and a tubular portion for housing and holding one end of the spiral portion, and the tubular portion is placed inside the cylindrical steel tube when the spiral pile and the foundation portion are integrated.

The invention according to claim 3 provides the structural foundation according to claim 2, which is characterized in that the fixing means is formed of a flange provided as a portion of the cylindrical steel tube or as a portion of the portion for receiving pressure in the horizontal direction, and a flange provided as a portion of the tubular portion, and the foundation portion and the spiral pile are connected when the flanges are connected and fixed to each other.

The invention according to claim 4 provides the structural foundation according to any of claims 1 to 3, which is characterized in that the portion for receiving pressure in the horizontal direction is formed of a cylindrical steel tube or formed by joining together sections of a steel H beam, a steel I beam, a steel channel and a steel angle.

The invention according to claim 5 provides the structural foundation according to any of claims 1 to 4, which is characterized in that the foundation portion has a portion for receiving pressure in the vertical direction, and the portion for receiving pressure in the vertical direction is a flat steel plate provided in a space between the cylindrical steel tube and the portion for receiving pressure in the horizontal direction.

The invention according to claim 6 provides the structural foundation according to any of claims 1 to 3, which is characterized in that a part including the cylindrical steel tube and a part including the portion for receiving pressure in the horizontal direction can be separated from each other.

The invention according to claim 7 provides the structural foundation according to claim 6, which is characterized in that the part including the cylindrical steel tube and the part including the portion for receiving pressure in the horizontal direction are linked together, the spiral pile is fixed to either the part including the cylindrical steel tube or the part including the portion for receiving pressure in the horizontal direction, and a space between the cylindrical steel tube and the portion for receiving pressure in the horizontal direction is filled in with concrete that has been poured so as to cover an area where the parts are linked together and an area where the spiral pile is fixed and solidified.

The invention according to claim 8 provides the structural foundation according to any of claims 1 to 7, which is characterized in that at least either one of the spiral pile and the fixing means of the foundation portion is provided with an installation angle adjusting means with which the angle at which the spiral pile is installed and fixed in the ground can be adjusted.

The invention according to claim 9 provides the structural foundation according to any of claims 1 to 8, which is characterized in that at least either one of the spiral pile and the foundation portion is provided with a structure adjusting means with which at least either one of the height or the degree of levelness of the supported structure can be adjusted while the structure is being installed.

Effects of the Invention

The invention according to claim 1 provides a structural foundation for supporting a structure or part of a structure, wherein the structural foundation has a foundation portion to be fixed to the ground using a spiral pile, and is characterized in that the foundation portion has a cylindrical steel tube for guiding the spiral pile and a portion for receiving pressure in the horizontal direction, which is placed so as to surround the cylindrical steel tube, and the foundation portion and the spiral pile are provided with a fixing means for connecting the foundation portion and the spiral pile in a state where the spiral pile is inserted into the cylindrical steel tube and the spiral pile is embedded in the ground, and therefore the integrated spiral pipe and the portion for receiving pressure in the horizontal direction makes it possible for the portion for receiving pressure in the horizontal direction to withstand stress in the horizontal direction and for stress placed on the spiral pile to be reduced. In addition, the cylindrical steel tube holds the spiral pile through the entirety of its length thus preventing the spiral pile from deformation caused by localized stress. Furthermore, this configuration can provide a structural foundation that is resistant to stress in the horizontal direction and can support the structure in a stable manner. Moreover, the spiral pile and the foundation portion can be easily combined at the construction site, and therefore a structural foundation with reduced cost for transportation and installation can be provided.

In the invention according to claim 2, the spiral pile has a spiral portion formed by twisting a flat steel plate and a tubular portion for housing and holding one end of the spiral portion, and the tubular portion is placed inside the cylindrical steel tube when the spiral pile and the foundation portion are integrated, and therefore the tubular portion can be used to guide the spiral pile smoothly into the cylindrical steel tube provided in the foundation portion. In addition, the tubular portion and the cylindrical steel tube work together to increase the strength of contact between the spiral pile and the foundation portion and to increase their integrity as a whole, and therefore a structural foundation that is more resistant to external stress including stress in the horizontal direction can be provided.

In the invention according to claim 3, the fixing means is formed of a flange provided as a portion of the cylindrical steel tube or as a portion of the portion for receiving pressure in the horizontal direction, and a flange provided as a portion of the tubular portion, and the foundation portion and the spiral pile are connected when the flanges are connected and fixed to each other, and therefore the foundation portion and the spiral pile can be connected and integrated without fail.

In the invention according to claim 4, the portion for receiving pressure in the horizontal direction is formed of a cylindrical steel tube or formed by joining together sections of a steel H beam, a steel I beam, a steel channel and a steel angle, and therefore it is possible to form a portion for receiving pressure in the horizontal direction that is more resistant to external stress in the horizontal direction placed on the structural foundation. In the case where a cylindrical steel tube is used, for example, when the steel tube is exposed to pressure, external stress in the horizontal direction placed on the structural foundation can be dispersed throughout the entirety of the steel tube thus preventing deformation caused by stress. In the case where a material having a high level of mechanical strength such as a steel H beam, a steel I beam, a steel channel or a steel angle is used, it is also possible to prevent a localized displacement in the portion for receiving pressure in the horizontal direction.

In the invention according to claim 5, the foundation portion has a portion for receiving pressure in the vertical direction, and the portion for receiving pressure in the vertical direction is a flat steel plate provided in a space between the cylindrical steel tube and the portion for receiving pressure in the horizontal direction, and therefore the flat steel plate receives external pressure in the vertical direction thus preventing deformation of the foundation in the vertical direction and also helping to avoid problems such as the structural foundation subsiding into the ground. In addition, it is possible to use the flat steel plate for linking the cylindrical steel tube to the portion for receiving pressure in the horizontal direction and thus the cylindrical steel tube and the portion for receiving pressure can be more solidly integrated.

In the invention according to claim 6, a part including the cylindrical steel tube and a part including the portion for receiving pressure in the horizontal direction can be separated from each other, and therefore parts that form the structural foundation can be broken down into a greater number of pieces, thus making it possible to further lower the cost for transportation.

The invention according to claim 7 is characterized in that the part including the cylindrical steel tube and the part including the portion for receiving pressure in the horizontal direction are linked together, the spiral pile is fixed to either the part including the cylindrical steel tube or the part including the portion for receiving pressure in the horizontal direction, and a space between the cylindrical steel tube and the portion for receiving pressure in the horizontal direction is filled in with concrete that has been poured so as to cover an area where the parts are linked together and an area where the spiral pile is fixed and solidified, and therefore the foundation can be fixed without fail after the installment of the foundation in the ground.

The invention according to claim 8 is characterized in that at least either one of the spiral pile and the fixing means of the foundation portion is provided with an installation angle adjusting means with which the angle at which the spiral pile is installed and fixed in the ground can be adjusted, and therefore the spiral pile can be installed and fixed in the ground easily while adjusting the angle of the spiral pile.

The invention according to claim 9 is characterized in that at least either one of the spiral pile and the foundation portion is provided with a structure adjusting means with which at least either one of the height or the degree of levelness of the supported structure can be adjusted while the structure is being installed, and therefore the structure can be installed by flexibly adjusting the height and the angle for installment in accordance with the purpose and objectives of the supported structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams illustrating the spiral pile for the structural foundation according the present invention;

FIGS. 2A and 2B are diagrams illustrating the foundation portion according to the first embodiment of the present invention;

FIG. 3 is a diagram illustrating the structural foundation according to the first embodiment of the present invention;

FIGS. 4A and 4B are diagrams illustrating the constructed state of the structural foundation according to the first embodiment of the present invention;

FIGS. 5A to 5E are diagrams illustrating the foundation portion according to the second embodiment of the present invention;

FIGS. 6A to 6D are diagrams illustrating the method for constructing the structural foundation according to the first embodiment of the present invention; and

FIGS. 7A to 7F are diagrams illustrating the method for constructing the structural foundation according to the second embodiment of the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION

In the following, the structural foundation according to the present invention is described in detail in reference to the preferred embodiments. In the description below, the same symbols are attached to the same members and accordingly the descriptions thereof are not repeated.

The present invention provides a structural foundation for supporting a structure or part of a structure. The structural foundation having a foundation portion to be fixed to the ground using a spiral pile is characterized in that the foundation portion has a cylindrical steel tube for guiding the spiral pile and a portion for receiving pressure in the horizontal direction, which is placed so as to surround the cylindrical steel tube, and the foundation portion and the spiral pile are provided with a fixing means for connecting the foundation portion and the spiral pile in a state where the spiral pile is inserted into the cylindrical steel tube and the spiral pile is embedded in the ground.

FIGS. 1A and 1B show an example of a spiral pile 1 used in the present invention. FIG. 1A is a front diagram showing the spiral pipe, and FIG. 1B is a top diagram showing the spiral pipe as viewed from the top. The spiral pile 1 is provided with a spiral portion 11 formed by twisting a flat steel plate and a flange 12 that becomes a fixing means for fixation to the below-described foundation portion. Furthermore, it is preferable for the spiral pile 1 to have a tubular portion 13 in order to increase the adhesion between the spiral pile and the foundation portion for greater stability when the spiral pile 1 is inserted into a cylindrical steel tube (described below) installed in the foundation portion.

As shown in the plan diagram in FIG. 1B, the fixing means 12 is provided with holes 14 for fixation to a fixing means installed in the portion for receiving pressure in the horizontal direction. In order to fix the spiral pile to the foundation portion, the spiral pile 1 is connected to the foundation portion and bolts are inserted into the holes 14 for fixation to the foundation portion. The spiral pile 1 is driven into the ground while being rotated where the angle of contact with the fixing means of the portion for receiving pressure in the horizontal direction fluctuates due to the rotation of the spiral pile, and therefore it is preferable for the holes 14 to be elongated as in FIG. 1B.

Next, the foundation portion according to the first embodiment of the present invention has a structure as in FIGS. 2A and 2B. FIG. 2A is a front diagram, and FIG. 2B is a plan diagram. As shown in FIG. 2A the foundation portion 2 according to the first embodiment of the present invention has a portion 21 for receiving pressure in the horizontal direction, which reduces external pressure in the horizontal direction that the spiral pile 1 receives from the ground, a cylindrical steel tube 23 for guiding the spiral pile, and a fixing means 22 for fixing the spiral pile to the foundation portion. In order to reduce pressure that the spiral piles receive from the ground, it is preferable for a portion 24 for receiving pressure in the vertical direction to be formed in a space between the cylindrical steel tube 23 and the portion 21 for receiving pressure in the horizontal direction.

In the present embodiment, a cylindrical steel tube is used for the portion for receiving pressure in the horizontal direction, and as a result external pressure in the horizontal direction that is received from the ground is dispersed equally throughout the entirety of the portion for receiving pressure in the horizontal direction, and therefore the entirety of the foundation portion 2 can be stabilized.

As shown in FIG. 2B, holes 25 for fixation to the fixing means 12 of the spiral pile 1 and holes 26 used to support a structure or part of a structure are created in the fixing means 22 of the foundation portion 2. In the present embodiment, the holes 25 are of a conventional size and are created closer to the center of the fixing means 22. The holes 26 are created closer to the outside of the fixing means 22, and the size and the locations thereof can be changed when appropriate depending on the relationship with the spiral pile and the supported structure. However, it is preferable for the holes to cover a certain area, for example as in the case of elongated holes, so that the installation angle of the supported structure can be adjusted appropriately, and in addition such means for adjusting the installation angle of the structure or the spiral pile may be provided in the fixing portion of the spiral pile instead of in the foundation portion 2. Furthermore, one hole can be used both for fixing the spiral pile and for fixing the structure.

When the foundation portion 2 and the spiral pile 1 are connected the foundation portion 2 is fixed in the ground and then the spiral pile 1 is inserted into the cylindrical steel tube 23 and the fixing means 12 of the spiral pile 1 and the fixing means 22 of the foundation portion 2 are joined to each other. When the fixing means 12 and 22 are joined to each other so that the spiral pile 1 and the foundation portion 2 are connected, the structure in FIG. 3 is gained. In the state where the spiral pile 1 is inserted into the cylindrical steel tube 23, the tubular portion 13 of the spiral pile and the cylindrical steel tube 23 work together so that the spiral pile 1 can be held in a stable manner. While bolts 31 are used in accordance with the method for joining the fixing means to each other in the present embodiment, flanges may be selected as the fixing means so that when appropriate a method that employs the welding of flanges together can be adopted.

When a structure or part of a structure is supported using the structural foundation according to the present invention, the structural foundation in FIG. 3 is installed in the ground and the structure or the part of the structure is fixed to the foundation for the structure. FIGS. 4A and 4B are diagrams illustrating a case where a support pillar, which is an example of a structure, is supported. In the case where a flange is provided to the support pillar the flange of the support pillar is fixed to the flange 12 of the spiral pile as in FIG. 4A so as to fix the support pillar. As for the fixation method at that time, when appropriate a method for using bolts 31 in the same manner as when the spiral pile is fixed to the foundation portion or a method of welding for fixation can be adopted.

In the embodiment shown in FIG. 4A double nuts 41 are used in order to connect the structural foundation 3 and the structure 4. When double nuts are used, the structure 4 can be installed while microscopically adjusting the height and the degree of levelness for installing the structure 4.

In the case where the spiral pile 1 of which part of the tubular portion 13 penetrates through the fixing means is used as in FIG. 4B, the support pillar can be supported by inserting the support pillar into the tubular portion 13 so that the support pillar is fixed in the tubular portion.

Next, the foundation portion according to the second embodiment of the present invention is described. The structural foundation according to the second embodiment of the present invention shown in FIGS. 5A to 5E is formed such that a part 5 including the portion 21 for receiving pressure in the horizontal direction that is formed by joining sections of a steel channel together and a part 55 including the cylindrical tube 23 can be separated from each other. The steel channel used for the portion 21 for receiving pressure in the horizontal direction itself has a high level of mechanical strength, and accordingly the portion for receiving pressure in the horizontal direction using the steel channel has a high level of mechanical strength so that external pressure in the horizontal direction received by the spiral pile from the ground can be reduced.

A fixing means 51 provided in the portion 21 for receiving pressure in the horizontal direction in the present embodiment is connected to an upper portion of the portion 21 for receiving pressure in the horizontal direction through a connection member 52, and holes 53 and 54 to be used for fixation to the fixing means of the spiral pile and to a structure or part of a structure are created in the same manner as in the first embodiment. In the lower portion of the part 5 including the portion for receiving pressure in the horizontal direction as shown in FIG. 5D, the fixing means 57 for fixture to the part 55 including the cylindrical steel tube is connected to the portion 21 for receiving pressure in the horizontal direction through connection members 52.

As shown in FIGS. 5A and 5D, the present embodiment adopts a configuration where the fixing means 54 and 57 are fixed to the portion 21 for receiving pressure in the horizontal direction through the connection members 52. As shown in FIG. 5E, however, a configuration can be adopted where a flat steel plate in which holes are created in advance is fixed to the portion 21 for receiving pressure in the horizontal direction.

In addition, the structural foundation according to the second embodiment of the present invention is formed so that the cylindrical steel tube 55 and the portion 5 for receiving pressure in the horizontal direction can be separated from each other. As shown in FIG. 5B, a fixing means 56 for fixation to the fixing means 57 of the portion for receiving pressure in the horizontal direction is formed in the cylindrical steel tube 55, and the part 55 including the cylindrical steel tube and the part 5 including the portion for receiving pressure in the horizontal direction are linked and fixed to each other by connecting the fixing means 57 and the fixing means 56, thus forming the structural foundation.

The cylindrical steel tube and the portion for receiving pressure in the horizontal direction can be separated from each other as in the present embodiment so that the structure can be assembled on site and thus a structural foundation can be easily provided with reduced cost for preparation and transportation.

While a steel channel is used for the portion for receiving pressure in the horizontal direction in the present embodiment, a steel H beam, a steel I beam or a steel angle can also be adopted when appropriate. The form of the fixing means and the method for connecting the fixing means are of course not limited to those in the present embodiment.

The construction method for installing the structural foundation according to the present invention in the ground is described below. Initially, a construction method for the structural foundation where a cylindrical steel tube is used as the portion for receiving pressure in the horizontal direction as in FIG. 3 is described in reference to FIGS. 6A to 6D. First, as shown in FIG. 6A, a foundation portion 2 is installed in the ground. At this time it is possible for the foundation portion 2 to be installed on the ground as it is without need for excavation. However, it is preferable for the ground to be excavated to a predetermined depth in order to firmly install the foundation portion 2 in the ground without fail. The depth of the excavation is not particularly limited as long as the foundation portion 2 can be fixed in the ground without fail, but it is preferable to excavate to such a depth that the top portions of all the members in the foundation portion are at the same level as the surface of the ground or at a level slightly lower than the surface of the ground.

After the foundation portion 2 has been fixed in the ground, the spiral pile 1 is inserted into the cylindrical steel tube 23 and the spiral pile 1 is driven into the ground while being rotated until the fixing means 12 of the spiral pile and the fixing means 22 of the foundation portion 2 make contact with each other. The spiral pile 1 and the foundation portion 2 are linked and fixed to each other by joining the fixing means 12 and the fixing means 22 to each other while adjusting the angle at which the spiral pile 1 is installed using the installation angle means provided in the spiral pile 1 or in the foundation portion 2.

After the spiral pile 1 and the foundation portion 2 have been combined, the structure 4 is placed on the upper portion of the structural foundation 3 and then the structure 4 and the structural foundation 3 are fixed to each other. As for the fixing means at this time, various methods can be adopted as described above, but it is preferable to use double nuts 41 so that the height and the degree of levelness can be adjusted while the structure 4 is being installed.

Finally, the space that has been created between the ground and the structural foundation as well as between the ground and the structure is filled in with a filler 6 such as concrete, mortar or rubble. As a result, the structural foundation installed in the ground can be more firmly fixed to the ground. When this filler covers the portion through which the structure and the structural foundation are linked together, the structure can also be more firmly fixed.

Next, a construction method for the structural foundation where the portion for receiving pressure in the horizontal direction and the cylindrical steel tube can be separated from each other as shown in FIGS. 5A to 5E is described. First, as shown in FIG. 7A, the part 55 including the cylindrical steel tube is firmly installed in the ground. At this time it is preferable to excavate the ground to a predetermined depth in the same manner as in FIGS. 6A to 6D.

In accordance with a method for fixing the part 55 including the cylindrical steel tube in the ground, as shown in FIG. 7B, the space between the cylindrical steel tube 23 and the ground is filled in with a filler 6 such as gravel or rubble, with which the ground is paved so that the part 55 including the cylindrical steel tube can be fixed to the ground.

Next, as shown in FIG. 7C, the part 5 including the portion for receiving pressure in the horizontal direction is linked and fixed to the part 55 including the cylindrical steel tube, thus forming the structural foundation. As for the method for linking and fixing, various methods according to which fixing means are combined by inserting bolts or by welding can be adopted as described above.

Thus, the spiral pile is inserted through the cylindrical steel tube and driven into the ground while being rotated so that the spiral pile 1 and the structural foundation are fixed to each other. The fixing method at this time is the same as that shown in FIGS. 6A to 6B, and the foundation portion and the spiral pile 1 are fixed to each other while adjusting the installation angle using elongated holes created in the foundation portion or the spiral pile 1. In addition, the spiral pile 1 may be fixed to either the part including the cylindrical steel tube or the part including the portion for receiving pressure in the horizontal direction, and the way for creating holes in the fixing means and the locations in which holes are created can be changed when appropriate.

Thus, the structure or the part of the structure is fixed to the structural foundation. As for the fixing method at this time, various methods can be adopted as described above, and it is preferable to fix the structure or the part of the structure to the structural foundation while adjusting the height and the degree of levelness of the structure using double nuts or the like.

Finally, concrete is poured into the space between the structural foundation and the ground and is left to solidify. As a result, the structural foundation can be fixed to the ground without fail. It is more preferable to pour the concrete so as to cover the points at which the structure or the part of the structure becomes joined to the structural foundation. As a result, the structure or the part of the structure can be fixed more firmly.

While the embodiments of the present invention are described above in reference to the given drawings, of course the design can be modified appropriately and different materials can be selected as long as the gist of the present invention is not deviated from.

INDUSTRIAL APPLICABILITY

The present invention can provide a structural foundation wherein a spiral pile for supporting the foundation can be fixed in such a stable manner as not to displace in the horizontal direction or not to subside in the vertical direction. In addition, the structural foundation can be easily installed on site with reduced costs for transportation and installment.

EXPLANATION OF SYMBOLS

-   -   1 spiral pile     -   2 foundation portion     -   3 structural foundation     -   4 structure     -   5 part including a portion for receiving pressure in the         horizontal direction     -   6 filler     -   7 concrete     -   11 spiral portion     -   12, 22, 51, 56, 57 fixing means     -   13 tubular portion     -   14, 25, 26, 53, 54, 58 hole     -   21 portion for receiving pressure in the horizontal direction     -   23 cylindrical steel tube     -   24 portion for receiving pressure in the vertical direction     -   31 bolt     -   41 double nut     -   55 part including a cylindrical steel tube 

1. A structural foundation for supporting a structure or part of a structure, comprising a foundation portion and a spiral pile, said foundation portion to be fixed to the ground using the spiral pile, wherein the foundation portion has comprises a cylindrical steel tube for guiding the spiral pile, and a portion for receiving pressure in a horizontal direction, which is placed so as to surround the cylindrical steel tube, and the foundation portion and the spiral pile are provided with a fixing means for connecting the foundation portion and the spiral pile in a state where the spiral pile is inserted into the cylindrical steel tube and the spiral pile is embedded in the ground.
 2. The structural foundation according to claim 1, wherein the spiral pile has a spiral portion formed by twisting a flat steel plate, and a tubular portion for housing and holding one end of the spiral portion, and the tubular portion is placed inside the cylindrical steel tube when the spiral pile and the foundation portion are integrated.
 3. The structural foundation according to claim 2, wherein the fixing means is formed of a first flange provided as a portion of the cylindrical steel tube or as a portion of the portion for receiving pressure in the horizontal direction, and a second flange provided as a portion of the tubular portion, and the foundation portion and the spiral pile are connected when the flanges are connected and fixed to each other.
 4. The structural foundation according to claim 1, wherein the portion for receiving pressure in the horizontal direction is formed of a cylindrical steel tube or formed by joining together sections of a steel H beam, a steel I beam, a steel channel and a steel angle.
 5. The structural foundation according to claim 1, wherein the foundation portion has a portion for receiving pressure in a vertical direction, and the portion for receiving pressure in the vertical direction is a flat steel plate provided in a space between the cylindrical steel tube and the portion for receiving pressure in the horizontal direction.
 6. The structural foundation according to claim 1, wherein a part including the cylindrical steel tube and a part including the portion for receiving pressure in the horizontal direction are separable from each other.
 7. The structural foundation according to claim 6, wherein the part including the cylindrical steel tube and the part including the portion for receiving pressure in the horizontal direction are linked together, the spiral pile is fixed to either the part including the cylindrical steel tube or the part including the portion for receiving pressure in the horizontal direction, and a space between the cylindrical steel tube and the portion for receiving pressure in the horizontal direction is filled in with concrete that has been poured so as to cover an area where the parts are linked together and an area where the spiral pile is fixed and solidified.
 8. The structural foundation according to claim 1, wherein at least either one of the spiral pile and the fixing means of the foundation portion is provided with an installation angle adjusting means with which the angle at which the spiral pile is installed and fixed in the ground is adjusted.
 9. The structural foundation according to claim 1, wherein at least either one of the spiral pile and the foundation portion is provided with a structure adjusting means with which at least either one of the height or the degree of levelness of the supported structure can be adjusted while the structure is being installed.
 10. The structural foundation according to claim 2, wherein the portion for receiving pressure in the horizontal direction is formed of a cylindrical steel tube or formed by joining together sections of a steel H beam, a steel I beam, a steel channel and a steel angle.
 11. The structural foundation according to claim 3, wherein the portion for receiving pressure in the horizontal direction is formed of a cylindrical steel tube or formed by joining together sections of a steel H beam, a steel I beam, a steel channel and a steel angle.
 12. The structural foundation according to claim 2, wherein the foundation portion has a portion for receiving pressure in a vertical direction, and the portion for receiving pressure in the vertical direction is a flat steel plate provided in a space between the cylindrical steel tube and the portion for receiving pressure in the horizontal direction.
 13. The structural foundation according to claim 3, wherein the foundation portion has a portion for receiving pressure in a vertical direction, and the portion for receiving pressure in the vertical direction is a flat steel plate provided in a space between the cylindrical steel tube and the portion for receiving pressure in the horizontal direction.
 14. The structural foundation according to claim 4, wherein the foundation portion has a portion for receiving pressure in a vertical direction, and the portion for receiving pressure in the vertical direction is a flat steel plate provided in a space between the cylindrical steel tube and the portion for receiving pressure in the horizontal direction.
 15. The structural foundation according to claim 2, wherein a part including the cylindrical steel tube and a part including the portion for receiving pressure in the horizontal direction are separable from each other.
 16. The structural foundation according to claim 3, wherein a part including the cylindrical steel tube and a part including the portion for receiving pressure in the horizontal direction are separable from each other.
 17. The structural foundation according to claim 2, wherein at least either one of the spiral pile and the fixing means of the foundation portion is provided with an installation angle adjusting means with which the angle at which the spiral pile is installed and fixed in the ground is adjusted.
 18. The structural foundation according to claim 3, wherein at least either one of the spiral pile and the fixing means of the foundation portion is provided with an installation angle adjusting means with which the angle at which the spiral pile is installed and fixed in the ground is adjusted.
 19. The structural foundation according to claim 4, wherein at least either one of the spiral pile and the fixing means of the foundation portion is provided with an installation angle adjusting means with which the angle at which the spiral pile is installed and fixed in the ground is adjusted.
 20. The structural foundation according to claim 5, wherein at least either one of the spiral pile and the fixing means of the foundation portion is provided with an installation angle adjusting means with which the angle at which the spiral pile is installed and fixed in the ground is adjusted. 